Brush holder



July 15, 1947. L. D. BRITTON 2,423,926

BRUSH HOLDER Filed Sept. 2, 1944 Snventor [522% ,0 fiviffoz y Gttomeg:

Patented July 15, 1947 BRUSH HOLDER Loren D. Britton,

eral Motors Corporation, poration of Delaware Application September 2, 1944, Serial No. 552,451

Hinsdale, Ill., assignor to Gen- Detroit, Mich, a cor- 4 Claims.

This invention relates to new and useful improvements in electrical brush holders.

The principal object of the present invention is to provide a simple, rugged brush holder assembly including adjustable brush tensioning 5 brush holder body I. Each brush 25 has a fleximeans in which a spring is included whereby a ble pigtail conductor 33 secured thereto and each brush may be supported and tensioned in proper of these conductors is connected to a separate manner and so that the spring may be rendered binding post 34 threaded in the body I. Each inoperative to tension the brush and then serve brush spring 2I comprises two helical coil porto hold a part of the tensioning means in a retions axially spaced apart on the shaft I5 betracted position in order to facilitate inspection tween the legs of each brush finger, a central and replacement of the brush. connecting 100p portion adapted to bear on the The form and arrangement of the elements outer end of the finger and upstanding end porcomprising the brush holder assembly by which tions. A spring adjusting lever 23 is pivoted at this object is accomplished and other novel feaits inner end on the shaft I5 between the two tures thereof will become apparent by reference helical coil portions of each spring :2I and a to the following detailed description of and acgrooved anchor p n 5 is s c ed to t e Out companying drawing illustrating the invention. end of the lever for connecting the upstanding Figure l of the drawing is a transverse cross ends of a Spring So that the spri exerts an sectional elevation view of the brush holder. angular separating force between a lever and a Figure 2 is a partial plan view of the brush finger. In order to anchor the spring adjusting holder with the end portions broken away and levers 23 in different angular positions on the Figure 3 is a partial end elevation View of the body to vary the spring force applied to the brush brush holder with the end and other portions fingers I9 an arcuate portion 31 having angubroken away to show certain details Of the ele- 5 larly spaced notches 39 is provided on the inner ments to better advantage. end of each lever, the arcuate portion 3! being The brush holder assembly comprises a body concentric to the shaft I5 and locking keys 4I member I, preferably formed by casting, having are .movably mounted on the body I adjacent a supporting boss 3 on one end provided with each of the levers by eans of locking studs 43. conventional insulated mounting studs, not Each of these keys are movable into e a e e shown, for attachment to the stator of a dynain any slot in the lever adjacent thereto and is moelcctric machine adjacent the commutator or clamped to the body by a separate locking stud a slip ring 5 of the machine rotor, shown in dot- 43. Each of the above described levers and leted lines in Figure 1. The body I is provided with ver locking means provide convenient means for a terminal boss I on the other end having tapped adjustment of the tension of each of the brush holes 9 for binding posts, not shown, by which springs. The keys 4| also serve as a stop to limit the main brush current conductor, not shown, the e acti g movement f t b s fi s I9 is connected thereto. A plurality of brush slots as each of these fingers are provided with a boss I I with a depression I3 alongside of each slot are 4 Wh ch C tacts O e Of the ysspaced longitudinally between the end of th 40 It will be noted that the flexible conductors 29 body I and a tubular shaft I5 is secured in aligned and 33 electrically connect each brush and finger openings in vertical transverse webs I I of the to the brush holder casting and it has been found body between each of the depressions I 3. that by use of a tube of Micarta or other insulat- Identical brush tensioning means comprising ing material for the tubular shaft I5 and bronze a fork-shaped brush finger I9, a brush spring brush fingers I9 free movement of the fingers rel- 2I and a spring tension adjusting lever 23 are ative to the tube is obtained as there is no leakrotatably supported on the shaft in each of the age current therebetween and no wear of the tube body depressions I3. The two legs of the forked or finger due to current leakage. inner end of each brush finger I9 are provided The two helical portions of each spring 2I are with aligned openings through which the shaft wound so that each portion is supported On the I5 extends and the outer end of each finger is Micarta tube I5 and is placed under compression provided with an arcuate tip, shown in contact between one side of a lever 23 and one leg of a with the outer end of a brush 25 in Figure 1. An finger I9 and accordingly one end coil of each upstanding boss or finger grip 21 is provided on helical spring portion frictionally engages one each finger to aid in retracting the finger from side of a lever 23 and the other end coil friction- 2 the brush. A flexible electrical conductor 25 is secured to the inner end of each finger and each of these conductors are electrically connected by a separate binding post 3| threaded into the ally engages one leg of a finger l9. With a lever 23 locked to the brush holder body I by means of a key 41 extending into one notch of the arcuate portion 31 of a lever 23, when the upstanding ends of the spring 2| are disengaged from the opposite ends of the lever anchor pin 35 the outer end of an adjacent finger 19 may be easily moved away from the brush 25 by means of the finger grip 21 and the finger IE) will be held in the fully retracted position with the finger boss 44 in contact with the key 4| by the frictional engagement exerted by the end coils of the spring 2| on the lever 23 and on the finger 19.

This feature enables the brushes to be readily removed for inspection or change in the confined spaces in which the brush holders are usually positioned. It will be evident that when the upstanding ends of a spring 2! are engaged with the opposite ends of a lever anchor pin the helical portions of a spring will be wound up and the central portion of the spring will engage the outer adjacent end of a finger and resiliently urge the arcuate outer end portion of the finger into contact with a brush 25 and hold the inner surface thereof in contact with the commutator 5. The force exerted by the spring 2| on a brush 25 may be varied by inserting the locking key 41 into different notches in the arcuate portion 3'! of the lever 23.

I claim:

1. A brush holder comprising a body having a brush slot extending therethrough, a brush finger and lever movably mounted on the body, means for locking the lever in diiierent positions with respect to the body and resilient means between and in frictional engagement with the finger and lever to frictionally hold the finger in different positions with respect to the brush slot and lever, said resilient means having portions adapted to be engaged with the lever and finger to urge the finger toward the brush slot and away from the lever.

2. A brush holder comprising a body having a brush slot extending therethrough, a brush finger and lever pivotally mounted on said body, means for locking said lever in different angular positions with respect to said body and a spring between and in frictional engagement with the finger and lever for frictionally holding the finger in different angular positions with respect to the lever and brush slot, said spring having portions adapted to be engaged with said lever and finger to cause said finger to be urged toward said slot and away from said lever.

3. A brush holder comprising a body having a brush slot extending therethrough and means located adjacent said slot for attaching a flexible brush conductor, a brush finger, spring, and spring adjusting lever supported for rotation on said body adjacent said slot, a flexible conductor connected between said finger and said body, said finger having an arcuate outer end portion movable into said brush slot and a forked inner end portion extending on opposite sides of said lever, means for locking said lever in different angular positions on said body, said spring having portions frictionally engaging the forked end of said finger and said adjusting lever to hold the outer arcuate end of said finger in a retracted position relative to said slot and portions adapted to be engaged with said finger and said lever to cause said spring to exert variable separating force between said finger and said adjusting lever depending upon the position of said lever to cause the outer arcuate end of said finger to be moved into said brush slot.

i. A brush holder comprising a body having a brush slot extending therethrough and means located adjacent said slot for attaching a brush conductor, an insulating shaft secured to said body adjacent said slot, a lever rotatably supported on said shaft, means for locking said lever in different angular positions with respect to said body, a brush finger having a forked end, the two legs of which are rotatably supported on said shaft either side of said lever and the other end of said finger having an arcuate tip adapted to enter the brush slot, a flexible conductor connected between said finger and body and a spring having two helical portions each supported on said shaft between the lever and one leg of the forked end of said finger and in frictional en agement with said finger and lever, a central portion engageble with the finger and end portions adapted to be connected with said lever to apply angular separating force between said lever and finger to urge the arcuate end of said finger toward the brush slot.

LOREN D. BRIT'ION.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 451,177 Emmet Apr. 28, 1891 727,571 Batchelder -1 May 12, 1903 1,150,486 Bergstrom Aug. 17, 1915 

